Karl Sebastian Greenwood, one of the key figures in crypto history’s most notorious Ponzi scheme, Onecoin, is going to spend two decades in prison. The sentence, imposed by U.S. District Judge Edgardo Ramos, was announced on Tuesday by United States Attorney for the Southern District of New York, Damian Williams. Greenwood co-founded Onecoin, which was based in Sofia, Bulgaria and started operations in 2014, together with Ruja Ignatova, a Bulgarian-born German national dubbed the “missing Cryptoqueen” as she is still at large. Onecoin marketed and sold a fake cryptocurrency by the same name through a global multi-level marketing (MLM) network.